1. Field of the Invention
The present invention relates to a cushioning member for protecting a device to be protected from shock, e.g. a hard disk drive, to a shock protection device including the cushioning members, and to portable information equipment incorporating the shock protection device.
2. Background Art
A hard disk drive (hereinafter referred to as a HDD) includes a disk rotating at high speeds, and a magnetic head. In the HDD, the magnetic head is moved in a head load state in which a predetermined spacing distance is provided from a disk surface of the disk and data is recorded into or reproduced from an intended recording position on the disk surface. To increase the recording density of the HDD, the amount of spacing provided when the magnetic head floats from the disk surface tends to be decreased year by year.
For this reason, especially when a shock load is imposed on the disk surface in the direction perpendicular thereto during operation of the HDD, the magnetic head is displaced in an amount larger than the spacing and likely to hit the disk surface. This phenomenon is called a head slap. Generally, the head slap can cause physical damage to the recording surface of the disk or the head. When the recording surface of the disk is damaged, data cannot be recorded into or reproduced from the damaged portion of the disk. In the worst case, all the recording surface of the disk cannot be used, that is, the HDD is broken.
When a HDD is incorporated and used in stationary information equipment represented by a desktop computer, a shock load causing the head slap is hardly imposed thereon. In contrast, a HDD incorporated in portable information equipment represented by a notebook personal computer (hereinafter a notebook PC) is always exposed to a shock load causing the head slap. In other words, a notebook PC features being carried and moved. A user thereof can carry and move the notebook PC easily. However, the user easily hits the notebook PC on a hard object, such as a corner of a desk, or drops the notebook PC inadvertently. A notebook PC is made light-weight and compact to ensure portability thereof. Because of this structure, a shock load causing the head slap can easily be transferred to the HDD incorporated in the notebook PC. As a result, the HDD may be broken.
In recent years, a small HDD to be incorporated into the notebook PC has a head retracting capability to increase shock resistance especially during operation. For a 2.5-inch HDD, for example, the magnetic head is retracted in a position spaced from the disk in an idling state, i.e. no access request for a predetermined period, irrespective of whether the HDD is in operation or not. For the retraction of the magnetic head, the magnetic head is moved into a retracting member that is disposed in a position spaced from the disk. In other words, the magnetic head is moved in a retracted position. Further, the magnetic head is locked in the retracted position. Such head retracting operation and locking operation is called head unloading operation. In this manner, the head unloading operation avoids the physical damage to the magnetic head or the disk surface that is caused by a shock load imposed on the recording surface of the disk in the direction perpendicular thereto.
In other words, as an operation mode, when the magnetic head need not be positioned on the recording surface of the disk, the head is retracted from the disk to prevent occurrence of the head slap.
While the magnetic head is accessing the disk (during operation of the HDD), the magnetic head is in a head load state. Therefore, when a shock load is imposed on the HDD in the direction perpendicular thereto during operation of the HDD, there is still high possibility of occurrence of the head slap and damage to the disk. For this reason, the head retracting capability is not effective in the HDD shock resistance when the user thereof inadvertently hits the notebook PC to the hard object or drops the notebook PC during operation of the HDD.
Further, the magnetic head or the disk surface can be damaged by small shock loads or frequently repeated vibrations daily applied to the HDD. The impact loads imposed daily include impact loads imposed when the notebook PC is placed on a desk, or carried in a bag.
FIG. 13A is a perspective view of notebook PC 110 incorporating conventional shock protection device 114 for hard disk drive 113 (hereinafter HDD 113). FIG. 13B is a perspective view of HDD 113 and shock protection device 114 of FIG. 13A. FIG. 13C is a perspective view of shock protection device 114 of FIG. 13A. FIG. 13D is a perspective view of shock protection device 114 of FIG. 13A. FIG. 14A is a perspective view of cushioning member 116 for use in shock protection device 114 of FIG. 13D. FIG. 14B is a sectional view showing a section taken on plane 14B of cushioning member 116 of FIG. 14A. FIG. 14C is a partially sectional view showing a section taken on plane 14C of shock protection device 114 of FIG. 13D.
As shown from FIGS. 13A through 14C, notebook PC 110 includes notebook PC body 111 and display 112. Notebook PC body 111 has some circuits including information processing circuits (not shown) therein. Display 112 has a liquid crystal panel (not shown) and some circuits including liquid crystal display circuits (not shown) therein. HDD 113 is covered by shock protection device 114 and housed in notebook PC 110. Shock protection device 114 includes inner case 114a and outer case 114b. 
Inner case 114a is made of packaging material 115 and cushioning members 116. Packaging material 115 is made of a thin sheet material of resin. For packaging material 115, the sheet material is cut, bent, and formed into a shape having a space therein. Housed in an inside space of packaging material 115 is a device susceptible to a shock load, such as HDD 13. Cushioning members 116 are attached to packaging material 115 by double-sided adhesive tapes. Cushioning members 116 include upper cushioning members 116u, lower cushioning members 116d, and side cushioning members 116s. Each of cushioning members 116 is a flexible material that is shaped like substantially a rectangular parallelepiped and has cushioning performance of undergoing compression deformation when being depressed. The materials of cushioning members 116 include special rubber, and foamed material, such as polyurethane foam. Both inner case 114a and HDD 113 are housed in outer case 114b. Outer case 114b is a box made of a metal, such as aluminum.
Shock protection device 114 thus structured houses a device susceptible to a shock load, such as HDD 13, and is incorporated in notebook PC body 111. With this structure, HDD 13 is protected from an extremely large shock load caused by a drop or the like. Further, HDD 13 is protected from small shock loads caused by daily actions, or frequently repeated vibrations.